1. Field of the Invention
The present invention relates to image pickup lenses and image pickup apparatuses, and more specifically to a technical field of an image pickup lens having a small size and improved optical performance, and an image pickup apparatus including the image pickup lens.
2. Description of the Related Art
Many of common image pickup apparatuses, such as camera-equipped mobile phones and digital still cameras, include charge-coupled devices (CCDs) and complementary metal-oxide semiconductors (CMOSs), for example, functioning as solid-state image pickup devices.
In recent years, there has been an increasing demand for size reduction in such image pickup apparatuses. Accordingly, image pickup lenses to be included in these apparatuses are desired to have short total optical lengths. In response to this trend, Japanese Unexamined Patent Application Publication No. 2007-155868 discloses an exemplary image pickup apparatus including a small-sized image pickup lens.
Together with the size reduction in recent small-sized image pickup apparatuses such as camera-equipped mobile phones, the number of pixels of image pickup devices included in the image pickup apparatuses has also been increasing. Apparatuses including image pickup devices of a so-called mega-pixel type having resolutions of at least one million pixels are becoming the mainstream.
Therefore, image pickup lenses to be included in such apparatuses are desired to have high lens performance so as to adapt themselves to the aforementioned image pickup devices having large numbers of pixels. Japanese Unexamined Patent Application Publication No. 2005-292559 discloses another exemplary image pickup apparatus including an image pickup lens having high lens performance.